High voltage DC links are often used for coupling electrical circuits of differing voltage under a common DC level. Typically, the capacitors used are able to withstand high DC voltages, often with high-frequency ripple voltages as well as a wide temperature range of operation. In known systems, electrolytic capacitors are commonly used in a series—parallel configuration such as that shown in FIG. 1. Often, screw terminal capacitors in combination with bus bars are used to connect the capacitor terminals to the rails of the circuits of interest. These are cumbersome and labour intensive arrangements to assemble.
The manufacturing tolerance of capacitors operating in a capacitor bank is particularly important. The voltages across each capacitor in the bank will be different due to differing manufacturing tolerance. The time before failure of a capacitor is related to the voltage and current conditions that the capacitor is subjected during its lifetime as would be understood by the skilled person.
In such systems of FIG. 1, a short circuit failure in, for example, capacitor C4 (the failure shown as reference numeral 20 in FIG. 2), could cause both capacitor C1 and capacitor C3 also to fail owing to the increased voltage across those capacitors. Such an initial failure in C4 could be due to old age. For example, if the capacitor has been exposed to a higher current and voltage than neighbouring capacitors, then that capacitor's time before failure will most probably be shorter due to electrolyte degradation. The capacitor could fail short circuit as shown. Often, the busbar connection 10 can retain conductivity even in the face of serious failure in the capacitor bank. This can act to increase unwanted damage to circuitry, not only in the capacitor bank, but elsewhere in the system.
Other disadvantages of using screw terminal capacitors in combination with a busbar include:                1) Failure of one of the capacitors causes a large amount of damage. The busbars can be bent due to the force of the explosion associated with the failure and a flash-over (electric arc) can occur owing to the large amount of un-insulated busbar. This can lead to increased collateral damage and hence additional circuit malfunction.        2) A failure in one capacitor can cause more than one other capacitor to fail.        3) Inefficient use of space (large diameter round screw terminal capacitors take up a relatively large amount of space because of the voids between the capacitor cans).        4) Higher cost due to the need to design-in and manufacture multiple screw connections.        
Therefore, a need arises for a more flexible, easier to manufacture, and less cumbersome arrangement for providing a DC link capacitor circuit where collateral damage in the case of a capacitor failure is limited.